Pedal bike with hinged front stem for additional power?
Many years ago I remember somebody riding a pedal cycle where the handlebar and stem assembly was hinged so that it could be pulled towards the rider's stomach (or maybe pushed away from it), thus giving a (small?) degree of additional power through some sort of ratchet system. I'm trying to find out if this was a one-off construction or if such bikes are/have been in production, but I don't know what they are called. I've searched for 'rowbikes', but these don't have the upright seated position that I recall. If they exist, then I'm sure someone on this particular sub-forum will be able to point me in the right direction!